Mordekovitz Yuval, Shelly Lee, Halabi Mahdi, Kalabukhov Sergey, Hayun Shmuel
Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 8410501, Israel.
Materials (Basel). 2016 Jun 16;9(6):481. doi: 10.3390/ma9060481.
The effects of lithium doping on the sintering and grain growth of non-stoichiometric nano-sized magnesium aluminate spinel were studied using a spark plasma sintering (SPS) apparatus. Li-doped nano-MgO·Al₂O₃ spinel ( = 1.06 and 1.21) powders containing 0, 0.20, 0.50 or 1.00 at. % Li were synthesized by the solution combustion method and dense specimens were processed using a SPS apparatus at 1200 °C and under an applied pressure of 150 MPa. The SPS-processed samples showed mutual dependency on the lithium concentration and the alumina-to-magnesia ratio. For example, the density and hardness values of near-stoichiometry samples ( = 1.06) showed an incline up to 0.51 at. % Li, while in the alumina rich samples ( = 1.21), these values remained constant up to 0.53 at. % Li. Studying grain growth revealed that in the Li-MgO·Al₂O₃ system, grain growth is limited by Zener pining. The activation energies of undoped, 0.2 and 0.53 at. % Li-MgO·1.21Al₂O₃ samples were 288 ± 40, 670 ± 45 and 543 ± 40 kJ·mol, respectively.
利用放电等离子烧结（SPS）设备研究了锂掺杂对非化学计量比纳米尺寸镁铝尖晶石烧结和晶粒生长的影响。通过溶液燃烧法合成了含0、0.20、0.50或1.00原子%锂的锂掺杂纳米MgO·Al₂O₃尖晶石（ = 1.06和1.21）粉末，并使用SPS设备在1200℃和150MPa的外加压力下制备致密试样。SPS处理后的样品显示出锂浓度与氧化铝与氧化镁比例之间的相互依赖性。例如，近化学计量比样品（ = 1.06）的密度和硬度值在锂含量达到0.51原子%之前呈上升趋势，而在富氧化铝样品（ = 1.21）中，这些值在锂含量达到0.53原子%之前保持恒定。对晶粒生长的研究表明，在Li-MgO·Al₂O₃体系中，晶粒生长受齐纳钉扎限制。未掺杂、0.2和0.53原子% Li-MgO·1.21Al₂O₃样品的活化能分别为288±40、670±45和543±40 kJ·mol。
